Lessons Learned Migrating from React CRA & Jest to Vite & Vitest

This article is for EDOCODE Advent Calendar 2024, published on 16th December 2024.

The previous article was written by Taiji Yamada, a Product Manager at EDOCODE: Automated Email System Using Notion Webhooks and the No-Code Tool "Make" (The article is in Japanese).

Also, please check out the Wano Advent Calendar by our parent group company!

Introduction

Our app, Gojiberry, is a Shopify survey app that helps merchants gather valuable feedback from their customers.

From the very beginning, we’ve built Gojiberry with test-driven development (TDD) to ensure our app is bug-free and that we can confidently release new features without breaking existing functionality. This foundation has allowed us to make large-scale changes, like migrating from Create React App (CRA) to Vite, with minimal disruption.

When CRA was deprecated, and its dependencies became outdated, we decided it was time to upgrade to a modern build tool that would better support our growing app. The large size of our codebase added some complexity, but the switch to Vite proved to be worth the effort.

Our goal was to migrate our two React projects:

• ? The Survey: Displayed to end-users to collect their responses.
• ? The Admin Dashboard: Used by merchants to configure surveys and view analytics.

If you're a Shopify store owner looking to gather actionable customer feedback, try out Gojiberry today on the Shopify App Store!

Motivation for the Migration

CRA served us well in the past, but it’s no longer maintained, and its dependencies have become outdated. This posed several challenges:

• ? Outdated libraries: We couldn’t update to critical libraries like user-events v14, which introduced significant improvements for handling async tests.
• ? Slow tests: Jest tests were getting slower over time, and we wanted the faster build and test times offered by Vite and Vitest.
• ⚖️ Inconsistent behavior: Across the two projects in our monorepo, both using the same user-events version, one required wrapping every action with act() while the other didn’t. This inconsistency created confusion and slowed development.

Key Changes in user-events v14

One of the biggest improvements in user-events v14 is the requirement to use await for all interaction methods. This eliminates the need for wrapping actions in await waitFor, making test code cleaner and easier to maintain.

Before (user-events v13):

import { render, screen } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import MyComponent from './MyComponent';

test('updates state on click', async () => {
  render(<mycomponent></mycomponent>);

  userEvent.click(screen.getByRole('button'));

  await waitFor(() => {
    expect(screen.getByText('Updated state')).toBeInTheDocument();
  });
});

After (user-events v14):

import { render, screen } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import MyComponent from './MyComponent';

test('updates state on click', async () => {
  render(<mycomponent></mycomponent>);

  userEvent.click(screen.getByRole('button'));

  await waitFor(() => {
    expect(screen.getByText('Updated state')).toBeInTheDocument();
  });
});

This change simplifies tests by removing the need to explicitly manage state changes with waitFor. Developers no longer need to think about when to include await waitFor, as the library automatically handles it.

The improvements in user-events v14 and Vitest addressed many of these issues, offering a cleaner, faster, and more consistent development experience.

Alternatives Considered

Before choosing Vite, we evaluated Next.js and Remix. While both are powerful frameworks, they required significant changes to our codebase and infrastructure:

• Next.js and Remix:

  • ? Codebase reorganization: Both frameworks required us to restructure our codebase to fit their conventions, which would have been a time-consuming process.
  • ?️ Infrastructure changes: These frameworks are not Single Page Application (SPA) frameworks, so adopting them would have required updates to our deployment and hosting infrastructure.
  • ⚖️ Overkill for our needs: While they offer great features for server-side rendering and routing, these features were unnecessary for our use case.

• Why we chose Vite:

  • ? Minimal code changes: Vite required almost no changes to our existing codebase, making the transition straightforward and efficient.
  • ?️ 1-to-1 compatibility with Jest: With Vitest being highly compatible with Jest, we could reuse most of our test code with minimal adjustments.
  • ⚡ Performance improvements: Vite provided faster build times, and Vitest significantly sped up test execution.

By choosing Vite, we avoided the complexity of adopting a full-fledged framework while reaping the benefits of a modern, lightweight build tool.

Migration Process

We approached the migration systematically since our monorepo contains two separate npm projects. Here’s how we executed the migration:

1. Start with the smaller project:

   • ?️ Migrating the smaller project first allowed us to identify potential pitfalls without risking the larger project.

2. Migration steps:
   
   The process for each project followed these steps:

   • ? Migrate to Vite: Replace CRA with Vite, fix any errors, and ensure the app builds and runs correctly.
   • ? Fix TypeScript errors: Vite introduced stricter TypeScript rules, exposing issues in the codebase. Fixing these made the code more resilient and reduced bad practices.
   • ✅ Migrate to Vitest: Transition tests from Jest to Vitest.
   • ? Fix test errors: Address any broken tests caused by differences in how Jest and Vitest handle certain scenarios.
   • ? Upgrade to user-events v14: Update the test library and fix broken tests. While many tests needed manual fixes, most issues stemmed from incorrect test cases, such as not waiting for React state changes when necessary. This was a valuable opportunity to spot and correct errors in our tests.

3. Repeat for the larger project:

   • ? After successfully migrating the smaller project, we applied the same steps to the larger project.

Challenges Encountered

• ? Broken tests: Migrating to Vitest and upgrading to user-events v14 caused numerous test failures. However, these failures revealed underlying issues in our test cases, such as missing await calls for React state changes. Fixing these improved the accuracy and reliability of our tests.
• ?️ TypeScript strictness: Vite’s stricter TypeScript rules exposed problematic patterns in our code. While it required extra effort to fix these errors, the end result was a cleaner and more resilient codebase.

Outcome

The migration from CRA to Vite, along with the transition to Vitest and user-events v14, has delivered substantial improvements to our development workflow:

• ⚡ Faster build and test times: After the migration, our test suite now completes in 30% less time, significantly speeding up our CI pipeline.
• ? Instantaneous hot reload: Vite's hot module replacement (HMR) during development is nearly instantaneous, a vast improvement over CRA, making development more seamless and efficient.
• ? Improved test clarity and reliability: The upgrade to user-events v14 and Vitest resulted in cleaner and more consistent tests. Many incorrect tests were fixed during the migration, helping us catch hidden bugs and improve overall code quality.
• ?️ Resilient codebase: Vite’s stricter TypeScript rules exposed several areas for improvement in our code, making the app more robust and reducing the likelihood of bad practices.

The migration has been a game-changer, allowing us to iterate faster while maintaining confidence in our codebase.

Lessons Learned

Here are some takeaways from our experience:

• ? Start small: Begin with smaller projects to reduce risks and refine the process.
• ⏳ Plan for broken tests: Expect some test cases to break and allocate time for fixing them. These failures often reveal deeper issues worth addressing.
• ?️ Embrace stricter rules: While stricter TypeScript rules and framework differences can initially feel like obstacles, they ultimately lead to a better codebase.
• ? Evaluate frameworks carefully: Choose tools that align with your existing architecture and goals.

Conclusion

Migrating from CRA to Vite and Vitest has brought significant improvements to our workflow. We now enjoy faster builds, cleaner test code with user-events v14, and a more resilient codebase thanks to stricter TypeScript rules.

One of the key factors that made this transition smoother was our early investment in test-driven development (TDD). With a comprehensive suite of tests in place, we were able to confidently make massive changes without breaking existing functionality.

If you’re considering a similar migration, we hope our experience provides valuable insights to guide your journey.

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Tomorrow, 17th December 2024, the article will be Switching from B2C to B2B: a marketers confession by Amee Xu, a Product Marketing Manager at Gojiberry.

At Wano Group, we are hiring! If you are interested, please check out our open positions using the link below:

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